>Every meaningful point might not be on the agenda, and refusing to have a pertinent discussion because it was not on the agenda will lead to a second or third meeting, who knows when, with revised agendas that still might no be good enough. That's largely inefficient and a time loss for everyone.
But this is exactly how it's supposed to work. It's efficient to table side discussions that don't apply to everyone. Otherwise, you're just wasting a subset of the participants' time.
A proper agenda should contain everything that absolutely needs to be talked about at that time. That is the focus of the meeting. If additional discussions are spawned that aren't covered by it, they should be taken offline, either with an additional meeting, or with an informal discussion after.
I guess your premise is that someone did extensive research before building the meeting agenda, communication by mail and other means allowed everyone to do one's homework, and everyone actually did it, so the meeting is really just to seal the consensus.
I agree in this kind of situation, unexpected items are of limited scope, shouldn't affect the meeting agenda, and can be dealt at other time.
Now, this would be more the exception than the rule, at least in my experience. And if you can reach this point in your organization, I think you can get rid of the meeting altogether, and just validate the different points by mail or group chat.
But this is exactly how it's supposed to work. It's efficient to table side discussions that don't apply to everyone. Otherwise, you're just wasting a subset of the participants' time.
A proper agenda should contain everything that absolutely needs to be talked about at that time. That is the focus of the meeting. If additional discussions are spawned that aren't covered by it, they should be taken offline, either with an additional meeting, or with an informal discussion after.